On January 21 Rocket Lab launched their latest Electron Rocket from the Mahia Peninsula. This rocket reached low earth orbit and contained their first commercial payload.  It also contained Peter Beck’s creation the ‘Humanity Star’. Rocket lab described this as;

“a geodesic sphere made of carbon fibre with 65 highly reflective panels... Orbiting the earth every 90 minutes and visible from anywhere on the globe, the Humanity Star is designed to be a bright symbol and reminder to all on Earth about our fragile place in the universe. ‘

The design was inspired by the phenomenon of Iridium Flares. These are the bright flashes that occur when light is reflected from a satellite that is part of the Iridium communications network. This was like a red rag to bull to some astronomers who have to deal with light pollution with some describing it as “space graffiti”.

These comments are perhaps a premature as there have been very few sitings of the the Humanity Star and it is estimated that it will be less biright than a typical pass by the International space station.

 

This is perhaps the first object sent into orbit with the sole purpose of being viewed for aesthetic or artistic purposes. However there are other similar projects such as Trevor Paglen‘s Orbital Reflector due to launch later this year or the Artssat1:Invader by the Tama Art University and The University of Tokyo launched in 2014 and now de-orbited. There was also a similar Russian crowdfunded satelite called Mayak which was launched in July 2017 but failed to deploy.

 

GEODESIC DOMES AND THE HUMANITY STAR

As well as debate on whether the Humanity Star was just expensive littering or an important artistic statement there was also debate on its geometry.
Some suggested it was the impressively named polyhedron, the “pentakis icosidodecahedron”, while others thought it was more likely a similar polyhedron known as the “penatakis pentagonal orthobirotunda”. Rocket Lab described it as having 65 reflective surfaces, which added to the confusion as both these objects have 80 faces.

 

Some architects and ageing hippies might recognise it as a type of geodesic dome. Specificaly the top half of Humanity Star is the same shape as a ‘2V icosahedron dome’. Many of the simpler geodesic domes are this shape.

The geometry of a geodesic dome is usually derived by taking an icosahedron (a regular polyhedron with 20 equilateral triangular faces) and dividing the faces into smaller triangles and projecting these onto the surface of a sphere. Below is a diagram showing this process. The 2v refers to how many times the face of the icosahedron is divided. This can also be done with any other of the 5 platonic solids (tetrahedron, cube, octahedron or docahedron) to produce different sorts of domes. It is worth noting that while the top half of half of the Humanity Star is the same as a the 2v icosahedron dome, there is a subtle difference between the a full geodesic 2v dome and the humanity star. The top half of the Humanity star is basicaly a mirror image of the top whereas in the geodesic dome the bottom half is rotated by 36 degrees.

 

 

 

There is an interesting relationship between this geometry and the golden ratio. The golden ratio is an irrational number which has a value of approximately 1.618 and is represented by the symbol phi (∅). It is defined as a ratio of lengths when the ratio of the longer length to smaller is equal to ratio of the sum of the lengths to the larger length. Many architects have the view that rectangles in this proportion are more aesthetically pleasing than rectangles of other proportions and so is has been used in the proportionsizing of windows, rooms and spaces for centuries. An icosahedron can be constructed by the intersection of 3 golden rectangles. Similarly the Humanity Star geometry can be generated with coordinates involving the golden ratio.

 

In their heyday Geodesic domes were for many people a sympbol of the prospect of a better way to live through technology, so perhaps this is an appropriate form for New Zeland first satelite.

Over the years this these domes have been continuously reinvented. Below are some of my favorites.